Dr. Rajendra Kapila, Professor of Medicine at Rutgers New Jersey Medical School, had been in practice for 50 years in New Jersey.
For 40 years, he was married to Dr. Bina Kapila before they divorced a decade ago.
She said her former husband was a brilliant doctor.
"He was so brilliant when we were in college, in medical school, that the professors of medicine after they gave a lecture, they would come to him and ask him, 'did I cover everything?'" she said.
Dr. Rajendra Kapila was 81-years-old, in the age group most vulnerable to the virus. He also had underlying conditions of diabetes and heart complications.
However, he decided to go to New Delhi for one week.
"What can go wrong in one week? So he was only going to go for one week," Dr. Bina Kapila said.
According to his biography on the Rutgers Health website, Dr. Rajendra Kapila was a founding member of the New Jersey Infectious Disease Society. He has also received the Excellence in Teaching Award from University of Medicine and Dentistry of New Jersey, and a Life Time Achievement award from the Department of Medicine.
Nancy Connell, Professor and Vice-chair for Research in the Division of Infectious Disease in the Department of Medicine at Rutgers New Jersey Medical School, expressed her thoughts on social media of the passing of her colleague.
"We have lost a giant in infectious disease, Dr Raj Kapila, who served for years as a leader in global infectious diseases at (Rutgers New Jersey Medical School). (Rutgers Biomedical and Health Sciences) will be ever grateful for his contribution to global ID and remember his extraordinary diagnostic talent," Connell tweeted this past Saturday.
Her tweet was retweeted by the Rutgers Medical School Twitter account.
We have lost a giant in infectious disease, Dr Raj Kapila, who served for years as a leader in global infectious diseases at @Rutgers_NJMS. @RutgersBHS will be ever grateful for his contribution to global ID and remember his extraordinary diagnostic talent https://t.co/5lYzDjxt9h— Nancy Connell (@ndconnell) April 29, 2021
It was not known if Dr. Rajendra Kapila was vaccinated prior to visiting India.
Bodies have been piling up at cremation grounds and in graveyards with relatives waiting for hours for the last rites.
With 382,315 new confirmed cases, India's tally has risen to more than 20.6 million since the pandemic began.
The Health Ministry on Wednesday also reported 3,780 deaths in the last 24 hours, bringing the total to 226,188.
Experts believe both figures are an undercount.
"It's so bad in India," Dr. Bina Kapila said.
The global community is extending a helping hand. The United States, Britain, Germany and several other nations are rushing therapeutics, rapid virus tests and oxygen to India, along with some materials needed for India to boost its domestic production of COVID-19 vaccines.
The Associated Press contributed to this report.